If you go
Joshua Tree National Park: http://www.nps.gov/jotr/ or 760-367-5500. There are three park entrances: West entrance five miles south of Highway 62 and Park Boulevard at Joshua Tree Village; North entrance in Twentynine Palms, three miles south of Highway 62 and Utah Trail; South entrance at Cottonwood Spring, 25 miles east of Indio, by Interstate 10.
Black Rock Canyon Campground at Joshua Tree: www.nps.gov/jotr/planyourvisit/blackrock.htm. Sites at Black Rock may be reserved Oct. 1-May 31. Reservations can be made up to six months in advance at www.recreation.gov/ or 877-444-6777.
Hidden Valley Campground at Joshua Tree: www.nps.gov/jotr/planyourvisit/camping.htm. Hidden Valley is one of several Joshua Tree campgrounds that are first-come, first-served year-round.
Anza-Borrego Desert State Park: www.parks.ca.gov/?page_id=638 or 760-767-5311. Entrance on eastern side of San Diego County is from Highway S2 south off Interstate 8. Reserve camping sites online at www.reserveamerica.com/. Reservations for Borrego Palm Canyon campground are required Oct. 1-April 30.